The present invention provides purified crystalline CCI-779 and processes for preparing same.
Rapamycin 42-ester with 3-hydroxy-2-(hydroxymethyl)-2-methylpropionic acid (CCI-779) is an ester of rapamycin which has demonstrated significant inhibitory effects on tumor growth in both in vitro and in vivo models. CCI-779 has been demonstrated to be effective in multiple applications, including as an anticancer agent for treating central nervous system cancer, leukemia, breast cancer, prostate cancer, melanoma, gliomas, and glioblastoma.
CCI-779 may delay the time to progression of tumors or time to tumor recurrence which is more typical of cytostatic rather than cytotoxic agents. CCI-779 is considered to have a mechanism of action that is similar to that of sirolimus. CCI-779 binds to and forms a complex with the cytoplasmic protein FKBP, which inhibits an enzyme, mTOR (mammalian target of rapamycin, also known as FKBP12-rapamycin associated protein (FRAP)). Inhibition of mTOR's kinase activity inhibits a variety of signal transduction pathways, including cytokine-stimulated cell proliferation, translation of mRNAs for several key proteins that regulate the G1 phase of the cell cycle, and IL-2-induced transcription, leading to inhibition of progression of the cell cycle from G1 to S. The mechanism of action of CCI-779 that results in the G1-S phase block is novel for an anticancer drug.
In vitro, CCI-779 has been shown to inhibit the growth of a number of histologically diverse tumor cells. Central nervous system (CNS) cancer, leukemia (T-cell), breast cancer, prostate cancer, and melanoma lines were among the most sensitive to CCI-779. The compound arrested cells in the G1 phase of the cell cycle.
In vivo studies in nude mice have demonstrated that CCI-779 has activity against human tumor xenografts of diverse histological types. Gliomas were particularly sensitive to CCI-779 and the compound was active in an orthotopic glioma model in nude mice. Growth factor (platelet-derived)-induced stimulation of a human glioblastoma cell line in vitro was markedly suppressed by CCI-779. The growth of several human pancreatic tumors in nude mice as well as one of two breast cancer lines studied in vivo also was inhibited by CCI-779.
CCI-779 has been purified by several recrystallization processes, which produce a form of CCI-779 that contains unacceptable amounts of impurities. Other routes to more purified CCI-779 include chromatography purifications, which provide a purer form of CCI-779. These chromatography purifications, however, cannot be scaled up to produce any appreciable amounts of purified CCI-779, nor would doing so be financially beneficially.
Alternate processes for preparing purified forms of CCI-779, especially processes performed on a larger scale, are needed.